On Wed, Mar 17, 2021 at 10:18:00AM +0100, Ingo Molnar wrote: > > * Yu, Yu-cheng <yu-cheng.yu@xxxxxxxxx> wrote: > > > On 3/16/2021 2:15 PM, Peter Zijlstra wrote: > > > On Tue, Mar 16, 2021 at 08:10:26AM -0700, Yu-cheng Yu wrote: > > > > Control-flow Enforcement (CET) is a new Intel processor feature that blocks > > > > return/jump-oriented programming attacks. Details are in "Intel 64 and > > > > IA-32 Architectures Software Developer's Manual" [1]. > > > > > > > > CET can protect applications and the kernel. This series enables only > > > > application-level protection, and has three parts: > > > > > > > > - Shadow stack [2], > > > > - Indirect branch tracking [3], and > > > > - Selftests [4]. > > > > > > CET is marketing; afaict SS and IBT are 100% independent and there's no > > > reason what so ever to have them share any code, let alone a Kconfig > > > knob. > > > > We used to have shadow stack and ibt under separate Kconfig options, but in > > a few places they actually share same code path, such as the XSAVES > > supervisor states and ELF header for example. Anyways I will be happy to > > make changes again if there is agreement. > > I was look at: > > x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states > > didn't see any IBT logic - it's essentially all shadow stack state. > > Which is not surprising, forward call edge integrity protection (IBT) > requires very little state, does it? They hid the IBT enable bit in the U_CET MSR, which is in the XSAVE thing.
